A ‘sublime’ new sustainable option for protective packaging

A cool new technology with freeze drying as a key part of the material manufacturing process is aimed at a number of markets including packaging. Compadre, a company known for transit packaging solutions, has obtained an exclusive license to pursue commercial uses for AeroClay, an innovative technology developed in a Case Western Reserve University materials lab. AeroClay technology turns clay and other ingredients like polymer into a versatile material that is sturdy, malleable, heat- and flame-resistant, as well as eco-friendly. It can be used as an absorbent, insulator or packing material, along with other uses.

AeroClay is also the name of a new company in Austin, TX, formed specifically for the commercialization of AeroClay technology. Although the company history is short, the AeroClay development team is long on experience in technology development and commercialization. The senior management team at AeroClay LLC's well-established parent company, Compadre, prides itself on bringing disruptive technologies to market. Compadre's mission is to capture big ideas to create new products in established markets.

AeroClay technology was invented in 2003 by David Schiraldi, Ph.D., chair of the department of Macromolecular Science and Engineering at Case Western Reserve University. In Austin, the company’s team of scientists is headed by Yuxin Wang, Ph.D., who worked in the Schiraldi lab at Case developing AeroClay in its early years. The first patent was filed in 2007, and so far, two U.S. patents have been issued with five WIPO (World Intellectual Property Organization) patents pending, which cover both applications and manufacturing processes for the AeroClay technology.

The AeroClay team of Yuxin Wang and Compadre’s Darryl Kelinske, CEO, and J. Gordon McGill, CFO, responds to Packaging Digest’s questions about this fascinating new material.

What is AeroClay?

AeroClay is a type of open-cell, flame-resistant foam made primarily from a clay and polymer mixture and created through an environmentally-friendly freeze-drying process. The AeroClay technology provides a new approach to designing and manufacturing foams without the need for the melt-extrusion and blowing agents required in traditional foam manufacturing processes, and it produces no toxic chemicals as byproducts. This green process creates virtually 100 percent raw materials yield with almost no manufacturing landfill waste and finished goods that can be biodegradable.

Clay and polymer are the two main components used to make AeroClay, and together they can form unlimited combinations and possibilities. Based on the raw materials used, AeroClay products are separated into two categories, a bio-series and a synthetic-series.

One of the most interesting AeroClay bio-series products in development is made from expired milk. Milk-based AeroClay provides a unique opportunity to repurpose an already wasted resource into an innovative, sustainable solution and to drastically reduce raw materials cost.

AeroClay synthetic-series products are designed for special applications such as chemical absorption and high temperature resistance. AeroClay can be made from polyvinyl alcohol, epoxy and many other polymers. Introduction of high-temperature and cross-linkable polymers helps improve the heat resistance; in addition to clay, additives such as inorganic fillers help, too. Different from traditional foam, which shows a honeycomb microstructure, AeroClay exhibits a layered structure whose voids can act as arrays of tiny capillaries for chemical absorption.

What are the basic steps in the AeroClay manufacturing process?

“Freeze-drying” is the main process used to make AeroClay. Freeze-drying is a well-developed technology in the food industry for making items such as instant coffee and in the pharmaceutical field for making vaccines, but it is rather new in the materials industry.

In the AeroClay manufacturing process, first clay and polymer are turned into an aqueous solution, then the aqueous solution is frozen into a solid with any desired shape, and finally the solid is placed into a freeze-drier where the ice is transformed into vapor. During this process, the ice helps create pores in the final product and works as a processing aid. When all of the ice is sublimed, the result is a lightweight, structural product called AeroClay. This process is waste-free—all the solid materials become product and the liquid is recyclable.

The most prominent components in AeroClay are bio-based materials, for example: cellulose (wood fiber), pectin (fruit extract), alginate (seaweed) and casein (milk), which are all biodegradable.

AeroClay is currently produced via a batch process, but we are very interested in developing a continuous manufacturing process.

What are the proposed or potential packaging applications?

AeroClay samples can be delivered in pellet, board and specially designed shapes. Currently, we are most interested in protective packaging and void-fill applications; but, considering the superior absorption and high temperature resistance of AeroClay, it is also highly suited for a variety of specialty applications, including hazardous materials containment and packaging. AeroClay can also be custom-formed in a sterile process and environment, so we are also open to market needs for edible, foam-like products and potential applications in the medical field.

What packaging properties can be engineered into AeroClay?

AeroClay has good mechanical performance and can be tailored to meet specific requirements, for either rigidity or flexibility, energy absorption and compression strength. These properties, combined with its light weight, thermal, flame-retardant and chemical absorption properties, make for a wide combination of properties and potential packaging uses.

How is that done?

AeroClay provides a platform technology; its advantages stem from its flexibility to choose and combine polymers and fillers because it eliminates the need for blowing agents used to create EPS foam, and it does not require exposure to any suspected carcinogens such as styrene.

Nearly any polymer that can form a thermodynamically stable aqueous colloid can be turned into an AeroClay foam using the AeroClay technology. In this process, it is easier to incorporate additional fillers without worrying about the nucleation that inhibits the widespread use of fillers in typical foams. For AeroClay, fillers can be reinforcement fibers or conductors, magnetics, fluorescent particles, and the like.

In what form can it be supplied? And what are costs?

Due to the versatility of the AeroClay process, specially molded shapes, sheet and board stock can be made. The material can be cut with traditional tools, machined and laminated to create even more complex shapes than can be molded directly.

We are targeted to be competitive in price compared to EPS and EPE foams, especially considering the lower cost of the rapidly renewable and abundant new materials utilized in many of the AeroClay processes and products.

What about the energy requirements and carbon footprint of the process?

Freeze-drying technology is widely used in the food and pharmaceutical industries. The freeze-drying process can be operated at room temperature and ultra-low pressure. Hot-melt processes are usually operated at high temperature and high pressure. At this point, there are only imprecise estimates of the relative energy efficiency of these two technologies, but we believe by eliminating both the high temperatures of a hot-melt process and the dangerous carbon-based byproducts produced in traditional foam manufacturing, the carbon footprint and energy requirements of AeroClay will be far superior to traditional polymer foams.

What is the materials’ end-of-life use?

The bio-series can be recycled back into the manufacturing process or composted by the end-users by simply burying it in the backyard. Some of the synthetic series, such as products containing polyvinyl alcohol, are biodegradable and recyclable back into the manufacturing process. The synthetic series products that are targeted for use in hazardous materials containment, cleanup and transport or in high-temperature applications can ultimately be used as fuels instead.

What is the current status? And what’s ahead?

The initial core research has been accomplished by Case Western Reserve University, and they continue to lead the way in research with their immense expertise in macromolecular engineering and polymer science. AeroClay is now building its primary lab and prototyping facility in Austin while concurrently developing a pathway for a continuous manufacturing process so that AeroClay products can be commercialized. Our focus is on the research and development necessary to take the products to market.

In addition to getting our Austin facility equipped for AeroClay development, we are actively working with potential customers on fully developing a number of near-term product varieties and applications during 2014. In 2015, we plan to begin releasing products to first adoption customers and on bringing full-scale, continuous process manufacturing online.

• Hazard-free foam insulation and fillers for medical use within a wide temperature range;

• Hazardous material absorbing foam for chemical transport;

And, for the not too distant future, we are already considering “edible foam” for food packaging and infant-related products.

Beyond its function as a product, AeroClay is truly an innovative technology; we are interested in working with other companies to develop and commercialize various applications.

Why is the timing good for this material now?

For years, the development of sustainable packaging has been hindered by the availability of raw materials that could be utilized in existing manufacturing processes. As a result, new sustainable materials have been difficult to commercialize. The natural tendency has been to view alternative materials with skepticism. In today’s world, progressive companies are realizing the economic, social and environmental benefits new products can provide and are eager to bring these products to market. Fortunately, new manufacturing processes, such as AeroClay, which deliberately incorporate the utilization of environmentally friendly raw materials, have started a new trend towards these kinds of products.

If we think outside of the box, technology innovation like AeroClay is the alternative route to sustainable packaging products. AeroClay technology provides a different way to solve the problem; many materials previously not feasible for the traditional hot-melt processes now become an option, and we face fewer obstacles to a sustainable future.